Drafting tables

ABSTRACT

Drafting tables for schools and colleges having steel frames with rear leg arrangements which ensure stability on uneven floors without special adjustment. The tables also all include a single ratchet associated with the frame, engageable by the lower end of a rod the upper part of which extends horizontally under the drawing board, and which is rotatable by a handle to release the lower end of the rod from the ratchet and to thus allow adjustment of the board angle. One embodiment includes a single rear leg and ratchet foldable into the plane of the front legs so that the whole table can be folded flat.

United States Patent [191 Douglas [4 1 Nov. 19, 1974 1 1 DRAFTING TABLES[21] Appl. No.: 324,839

283,083 5/1952 Switzerland 108/6 142,745 11/1903 Germany 108/4 63,8305/1913 Switzerland 108/9 210,074 3/1924 Great Britain..... 248/188228,941 12/1902 Great Britain 108/6 1,239,237 10/1959 France 1 108/8Canada 108/6 Primary Examiner-Paul R. Gilliam Attorney, Agent, orFirm-Stevens, Davis, Miller & Mosher [57] ABSTRACT drawing board, andwhich is rotatable by a handle to release the lower end of the rod fromthe ratchet and to thus allow adjustment 'of the board angle. Oneembodiment includes a single rear leg and ratchet foldable into theplane of the front legs so that the whole table can be folded flat.

3 Claims, 14 Drawing Figures i/ /3Z /3 I E J 35 l 26 [52] U.S. Cl. 108/6[51] Int. Cl. A47f /12 [58] Field of Search 108/1-10, 115;

[56] References Cited UNITED STATES PATENTS 196,381 /1877 Plluegner .1248/397 418,687 1/1890 Collins 656,256 8/1900 Leisenring 987,113 3/1911Cooley 1,184,594 5/1916 Nagy 1,399,706 12/1921 Ellison 2,016,571 10/1935Barrett 2,630,360 3/1953 McGinley 2,686,094 8/1954 Terry 2,912,04611/1959 Fuerst 3,473,491 10/1969 Grzywacz 108/6 FOREIGN PATENTS ORAPPLICATIONS 205,642 10/1923 Great Britain 108/9 PATENTtLmvlslsm3,848,544 SHEET 30F 6 DRAFTING TABLES This application is acontinuation-in-part of my US. Pat. application Ser. No. 172,184 filedAug. 16, 1971, now abandoned.

The present invention relates to a table, and particularly to a draftingtable for use in schools and colleges.

Drafting tables at present in use generally have four fixed legs. Suchtables are apt to rock either due to inaccuracies of manufacture, or dueto uneveness of the floor on which they rest, so that normally suchdrafting tables require adjustment means for one leg in order to besatisfactory.

An object of the present invention is to provide a table, particularly adrafting table, of simple construction which is quite stable on unevenfloors, and requires no adjustment of its legs.

Other objects of the invention are to provide tables with improvedratchet arrangements for adjusting the angle of the table top or boardmeans, and to provide a foldable table having these features.

In accordance with one aspect of the present invention, in a tablehaving a support frame and board means mounted on the support frame bypivot means allowing tilting of the board means about a horizontal axis,said board means is adjustable to a variety of angular positionsrelative to the support frame by means including a single ratchetmounted on the frame, a rod having an upper shaft portion extendinghorizontally under the board means and rotatably attached thereto, therod having a lever portion extending downwardly from said upper shaftportion and having ratchet engaging means at its lower end engageableand disengageable with said ratchet on rotation of said shaft portion,and handle means for rotating said shaft portion.

Preferably, the support frame includes a front cross member rigidlyconnecting upper portions of the front leg members, and a further memberextending rearwardly from the cross member and having the rear leg meansconnected onto its rear end. The rear leg means may be a simple singlerear leg, or may include a rear upright member extending downwardly fromthe rearwardly extending member, a rear cross member mounted for limitedangular movement on said upright member, and rear feet attached to theouter ends of said rear cross member.

The limited angular movement of the rear cross member is preferably ofthe order of 1.

Where the rear leg means is a single rear leg, the rearwardly extendingmember may be hingedly attached to the cross member, to allow the wholetable to be folded flat.

It will be understood that the term front" refers to the side of thetable at which the person using the table normally stands, the rearofthe table being the opposite side.

A further feature of tables in accordance with the invention is that theboard means comprises a flat board, for example of wood or plastic,supported by stiffening means including two brackets spaced apart andextending fore-and-aft of the board, the brackets being rigidlyconnected by a bar which is sufficiently stiff in torsion to preventwarping of the board itself. The brackets each include a dependingflange which also serves to connect the board means with hinge meanscarried by the support frame.

The invention will be particularly described with reference to theaccompanying drawings, in which;

FIG. 1 shows a perspective view of a first embodiment of drafting tablein accordance with the invention,

FIG. 2 shows a front view of the table,

FIG. 3 shows a side view of the table,

FIG. 4 shows a top, plan view of the table,

FIGS. 5 and 6 show detailed side views of part of rear leg means,

FIG. 7 shows a perspective view of a second, simpler drafting tableusing a similar board and hinge arrangement,

FIGS. 8 and 9 show, respectively, front and side views of the table ofFIG. 8,

FIG. 10 shows a top plan view of the table of FIG. 8,

FIGS. 11, 12 and 13 show respectively side, rear and top plan views of athird embodiment of drafting table, and

FIG. 14 shows a perspective front view of the third embodiment ofdrafting table when folded flat.

Referring to FIGS. 14 of the drawings, a drafting table is shown havingdrawing board means 10 mounted for tilting movement about a horizontalaxis on a support frame 11, this axis being adjacent the front edge ofthe board means. The support frame comprises two upright front legmembers 13, a cross member 14 connecting the upper portions of the legmembers 13, a member 15 extending rearwardly from the center of crossmember 14, and a single, central, rear leg means 17 extending downwardlyfrom the rear end of member 15. The rear leg means comprises a rearupright member 18 extending downwardly from the member 15, a rear crossmember 19 mounted at 20 for limited angular movement on member 18, andrear feet 21 attached to the outer ends of the rear cross member. Themembers 13, l4, l5 and 18 are all formed of 1 inch square section 18gage steel tubing, securely welded together to make a rigid structure.The top of leg member 18 extends above the level of the horizontalmembers 14 and 15, and is capped with a resilient cap to form a supportfor the rear edge of the board means 10.

The drawing board means 10 comprises a flat board 24 of 5/6 inch thickMacrolite (trademark), fixed to stiffening means comprising two anglemember brackets 25 and 26 extending fore and aft of the board andadjacent to the side edges of the board, and joined at their rear endsby a torsion bar 27 of 1 inch steel tubing securely welded to thebrackets. The brackets have their horizontal flanges securely fixed tothe board, and the bar 27 is sufficiently stiff in torsion to preventany substantial warping of the board. The brackets 25 and 26 each have avertical flange which increases in depth towards the front edge of thetable. The lower front corner of each of the vertical flanges ispivotally secured to the outside of a front leg member at a point justabove the cross member 14, in such manner as to allow tilting movementof the board about a horizontal axis parallel to the cross member. Thepivot means attaching the brackets to the leg members 13 include afibre, friction washer, and a conical, resilient pressure washer, whichare tightened to give sufficient frictional resistance to pivoting ofthe board to prevent the board dropping under its own weight.

Beneath the rearwardly extending member 15 is attached a single verticalratchet 29, comprising a sheet steel member having a vertical slot witha series of notches in the rear edge of the slot. As will be clear fromthe drawings, the ratchet is located in a central position between theside edges of the board means 10. The ratchet is engageable by means atthe end of a lever formed by the lowest part 30 of a rod 31 which ispivotally mounted on the board means. The rod 31 has an upper shaftportion 32 extending horizontally under the board means, parallel to thefront edge of the board, and held by small brackets 33 so as to berotatable about its own axis. The lever portion 30 of the rod is bent at90 to the shaft portion and extends downwardly from one end of the uppershaft portion and terminates in ratchet engaging means constituted by abent-in end which engages with the notches of the ratchet 29. The outerupper end of the rod is bent to form a handle 35 situated under theright hand side of the board, so as to be convenient to the user of theboard.

At the junction between the shaft portion 32 and the lever portion 30 ofthe rod there is welded one end of a flexible thin rod or wire 36, theother end of which is bent at 90 and secured to the underside of theboard. Before being secured in this manner, the wire 36 is subjected totorsion, in such direction as to urge the lever 30 against the notchesof the ratchet 29, so that this wire 36 forms a spring which holds thelever in the appropriate notches of the ratchet.

FIG. and 6 show details of the joint between the rear upright member 18and the rear cross member 19. The joint includes two side plates 38welded to the lower end of member 18 and extending below this lower endto form a recess for receiving the cross member 19. The member 19 issecured to the plates 38 by a pivot pin 39 passing horizontallyfore-and-aft through holes in the plate 38. Thin washers are mountedbetween the plates 38 and the member 19, to prevent looseness in theassembly. The clearance space between the top of member 19 and the lowerend of member 18 is sufficiently small (about l/64 of an inch), so thatthe angular movement of the cross member is limited to a few degrees,and preferably is of the order of l.

In operation, the tilted position of the drawing board can be adjustedby holding the board with two hands, with the fingers of the right handholding the handle 35 and pressing this upwards, towards the board, todisengage the lower end of the lever 30 from the ratchet, so that theboard can readily be adjusted to any tilted position.

The self-levelling nature of the rear leg means in practice ensures thatthe drafting table is steady even when placed on somewhat uneven floors,and no special adjustment of the leg means is necessary.

FIGS. 7 to 10 illustrate a somewhat similar drafting table to that ofFIGS. 1 to 6, but in which a simple, single rear leg is provided insteadof the self-levelling rear leg means of the first embodiment.

Referring then to FIGS. 7 to 10, the drafting table has a drawing boardmeans 110 mounted for tilting movement about a horizontal axis on asupport frame 111. The support frame comprises two upright front legmembers 113, a cross member 114 connecting the upper portions of the legmembers, a member 115 extending rearwardly from the center of crossmember 114, and a single, central rear leg member 117 extendingdownwardly from the rear end of member 116. The

members 113, 114, and 117 are all formed of 1 inch square section 18guage steel tubing, securely welded together to make a rigid structure.The top of leg member 117 extends above the level of the horizontalmembers 114 and 115, and is capped with a resilient cap 118 to form asupport for the rear edge of the board means 110.

The drawing board means 110 comprises a flat board 20 of 5/8 inch thickMacrolite (trademark), fixed to a stiffening means comprising two anglemember brackets 121 and 122 extending fore and aft of the board, andjoined at their rear ends by a torsion bar 123 of 1 inch steel tubingsecurely welded to the brackets. The brackets have their horizontalflanges securely fixed to the board, and the bar 123 is sufficientlyresistant to torsional deflection to prevent any substantial warping ofthe board. The brackets 121 and 122 each have a vertical flange whichincreases in depth towards the front edge of the table. The lower frontcorner of each of the vertical flanges is pivotally secured to theoutside of the front leg at a point just below the cross member 114, insuch manner as to allow tilting movement of the board about a horizontalaxis parallel to the cross member. The pivot means attaching thebrackets to the leg members 113 include a fibre, friction washer, and aconical, resilient pressure washer, which are tightened to givesufficient frictional resistance to pivoting of the board to prevent theboard dropping under its own weight.

Inside the rear leg member 117 is attached a vertically extendingratchet comprising a sheet steel member having a vertical slot with aseries of notches in the rear edge of the slot. The ratchet isengageable by means at the end of a lever formed by the lowest part 125of a rod 126 which is pivotally mounted on the board means. The rod 126has an upper shaft portion 127 extending horizontally under the boardmeans, parallel to the front edge of the board, and held by smallbrackets 128 so as to be rotatable about its own axis. The lever portion125 of the rod is bent at 90 to the shaft portion and extends downwardlyfrom the board and terminates in a bent-in end which engages with thenotches of the ratchet. The outer upper end of the rod is bent to form ahandle 129 situated under the 'right hand side of the board, so as to beconvenient to the user of the board.

At the junction between the shaft portion 127 and the lever portion 125of the rod there is welded one end of a flexible thin rod 130, the otherend of which is bent at 90 and secured to the underside of the board.Before being secured in this manner, the rod is subjected to torsion, insuch direction as to urge the lever portion 125 of the rod 126 againstthe notches of the ratchet, so that this flexible rod 130 forms a springwhich holds the lever in the appropriate notches of the ratchet.

In operation, the tilted position of the drawing board can be adjustedby holding the board with two hands, with the fingers of the right handholding the lever 129 and pressing this upwards, towards the board, todisengage the lower end of the lever 125 from the ratchet, so that theboard can readily be adjusted to any tilted position up to the nearlyvertical position shown in FIG. 9.

The drafting table shown in FIGS. 11 to 14 is somewhat similar to thepreviously described embodiment, but is adapted to be folding.

right front leg members 213 and a cross member 214.

rigidly connecting upper portion of these by members. The frame alsoincludes, as in the previous embodiment, a rearwardly extending member215 from the rear end of which extends a single central rear leg member217, these latter members together constituting rear leg means for thetable. However, in this embodiment, the member 215 is hingedly connectedto cross member 214 for movement relative to the cross member about avertical axis (i.e., an axis which is vertical when the table is in itsoperating position), the member 215 being hinged to the cross member bybolt means 215a at a position near to one of the upright front legmembers, and in the operating position both the member 215 and the rearleg member 217 extend obliquely away from the cross member so that thelower end or foot of the member 217 is underneath the centre of the rearof the board means (see FIG. 13).

,The rear leg member 217 is also'oblique to the member 215 when seen inside view, and the members 215 and 217 can be pivoted about bolt means2150 into the folded position shown in FIG. '14 in which the members 215and 217 are parallel to the plane of the front leg members and in whichfoot-of member 217 is adjacent the foot of thatupright member on theopposite side of the table from bolt means 215a. It will also beapparent from FIG. 14 thatv the members 215 and 217, when in thefolded'position, are wholly within the outer boundaries of the plane ofthe front leg members 213. Furthermore, since member 215 foldsunderneath member 214, the'members 215 and 217 are contained entirelywithin the space bounded by the front leg members and the cross memberso that the folded support frame has a thickness substantially the sameas the fore-and-aft width of the leg members.

The board means 210, and the rnanner of attachment of the board meanstothe frame, are similar to those of the previously described embodiments,except for the use of short brackets 225a connected to the upper endsoflegs 213 by pivot means, and the absence of any torsion bar. Thesepivot means permit folding of the board means flat against the foldedframe as illustrated in FIG. 14. g

The means for maintaining the board means in a variety of angularpositionsincludes a ratchet 229 attached to the rear leg member 217 andhaving rearwardly facing notches. The ratchet is engageable byalowermost, horizontal portion 230a of the lever portion 230v 'of a bentrod 231. The rod 231 includes two upper horizontal portions 232extending horizontally under the board means and connected thereto bysmall brackets 233 which allow rotation about the axis of portions 232;two legs of .lever portion 230 extending downwardly from the board whenthe table is in use; and the connecting. lowermost portion 2300. Inaddition, the outer ends of rod 231 provide two handles 235 for rotatingthe portions 232 and disengaging portion 230a from the ratchet. I v r [nthis embodiment, no spring is needed to urge the ratchet engaging rodportion 230a into the notches of the ratchet, since the slope of theratchet ensures-that such movement occurs under gravity. v v

The table is used in similar manner to that of FIGS. 7 to 10. However,for shipping or storing the table, this can be folded into the flatcondition of FIG.114. This is achieved simply by release of the rodportion 230a from the ratchet and then folding this rod flat against theboard means, folding of the rear leg member 217 about the vertical axisof bolt means 215a into the plane of leg members 213, and finallyfolding of the board means 210 flat against the leg members 213 bypivoting it about its pivoted axis which is parallel to cross member214.

It is not of course essential that the rearwardly extending member 215be connected directly to the cross member 214; indirect connection via abracket attached to a'front leg member 213 would also serve the purpose.

It may be noted that the drafting tables are of extremely simpleconstruction, using a frame work having few joints, but which arenevertheless quite stable. The means for maintaining the board in anumber of tilted positions is also simple in construction and operation,

particularly by virtue of the association of the ratchet means with therear leg means. The provision of a single, central, ratchet means is incontrast to many previous designs for drafting tables, which require theuse of two ratchets, one at each side of the table,'which have to beoperated simultaneously.

I claim: l 1. A drafting table comprising: r

a. a support frame including two upright front leg members and. a crossmember rigidly connecting upper portions of said leg members and singlerear leg means extending downwardly and rearwardly ,from said crossmember in an operative position thereof, I

. a single normally vertical pivotconnecting said single rear leg meansto said cross member, the upper 7 forward end of said rear leg meansbeing mounted underneath said cross member and said rear leg means beingdimensioned to allow said rear leg means to be folded by movement aboutsaid pivot into a position parallel to the front leg members and whollywithin the outer boundaries of the front leg members and said crossmember,

c.- means-defining a series of notches spaced along said rear leg meansso that said notches have openings rearwardly of the rear leg means whenthe rear leg means is in its operative position,

d. board means mounted on the support frame by pivot means allowingtilting of the board means about a horizontal axis adjacent a front edgeof the board means, said pivot means allowing adjustment of the angularposition of the board means to a variety of sloping operative positionsand also allowing folding of said board means into a position close toand parallel to said front leg members, and

e. adjustment means mounted on said'board means for adjustment thereofrelative to said rear leg positions, and said rod having handle means atthe other end of said shaft portion for rotating said shaft portion tocontrol engagement of the lower horizontal portion with said notches,said lever portion being disengageable from said notches and pivotalagainst the underside of said board means for folding of the t able, W

whereby said table can be folded by disengagement of the lowerhorizontal rod portion from the notches, folding of the rear leg meansparallel to the plane of the front leg members, pivoting of the rodlever portion against the board means and then pivoting of the boardmeans flat against the leg members.

2. A table according to claim 1, wherein said rear leg means is pivotedto said cross member at a position near to one of said upright front legmembers, and wherein, with the rear leg means in the folded position,the lower end of the rear leg means is adjacent the lower end of theother upright front leg member.

3. A table according to claim 1, wherein, in the folded condition, therear leg means is contained entirely within the space bounded by thefrontleg members and the cross member, whereby the folded support framehas a thickness substantially the same as the foreand-aft width of thefront leg members.

1. A drafting table comprising: a. a support frame including two uprightfront leg members and a cross member rigidly connecting upper portionsof said leg members and single rear leg means extending downwardly andrearwardly from said cross member in an operative position thereof, b. asingle normally vertical pIvot connecting said single rear leg means tosaid cross member, the upper forward end of said rear leg means beingmounted underneath said cross member and said rear leg means beingdimensioned to allow said rear leg means to be folded by movement aboutsaid pivot into a position parallel to the front leg members and whollywithin the outer boundaries of the front leg members and said crossmember, c. means defining a series of notches spaced along said rear legmeans so that said notches have openings rearwardly of the rear legmeans when the rear leg means is in its operative position, d. boardmeans mounted on the support frame by pivot means allowing tilting ofthe board means about a horizontal axis adjacent a front edge of theboard means, said pivot means allowing adjustment of the angularposition of the board means to a variety of sloping operative positionsand also allowing folding of said board means into a position close toand parallel to said front leg members, and e. adjustment means mountedon said board means for adjustment thereof relative to said rear legmeans, said adjustment means including a rod having an upper shaftportion extending horizontally under the board means, said upper shaftportion being positioned close to the board means and rotatably mountedthereon, said rod having a lever portion extending downwardly from oneend of said shaft portion and having a lower horizontal portion at itslower end, said lower horizontal portion being suitable for engagementwith the notches of said rear leg means when the board means and therear leg means are in their operative positions, and said rod havinghandle means at the other end of said shaft portion for rotating saidshaft portion to control engagement of the lower horizontal portion withsaid notches, said lever portion being disengageable from said notchesand pivotal against the underside of said board means for folding of thetable, whereby said table can be folded by disengagement of the lowerhorizontal rod portion from the notches, folding of the rear leg meansparallel to the plane of the front leg members, pivoting of the rodlever portion against the board means and then pivoting of the boardmeans flat against the leg members.
 2. A table according to claim 1,wherein said rear leg means is pivoted to said cross member at aposition near to one of said upright front leg members, and wherein,with the rear leg means in the folded position, the lower end of therear leg means is adjacent the lower end of the other upright front legmember.
 3. A table according to claim 1, wherein, in the foldedcondition, the rear leg means is contained entirely within the spacebounded by the frontleg members and the cross member, whereby the foldedsupport frame has a thickness substantially the same as the fore-and-aftwidth of the front leg members.